Pivotable pack frame apparatus

ABSTRACT

A pack frame apparatus having first and second frame portions configured to be secured to a backpack, wherein the first and second frame portions provide structural rigidity to the backpack when secured to the backpack. The first frame portion is configured to be secured to shoulder straps of the backpack, and the second frame portion is configured to be secured adjacent to a waist strap of the backpack. A joint joins the first and second frame portions to allow relative pivotal movement around a first axis and to allow resilient relative pivotal movement around a second axis.

BACKGROUND

The following relates generally to support systems for packs and specifically to a multi-piece pivotable support frame for a backpack.

Historically, external frame pack designs have been made from tubes made of aluminum or another light, rigid material. These packs are good for bearing heavy loads and directing the loads to the hips of the wearer. Pack frames for external frame packs are typically spaced away from the wearer's body due to the rigid shapes used. Skiing, hiking, running, and other dynamic activities may be more difficult using a non-conforming pack due to swaying of the pack (even when strapped to the wearer) and the weight of the pack being spaced from the wearer's body. The spaced center of gravity of the pack from the wearer's body may throw the wearer off-balance or cause unnecessary fatigue by its swaying and other motion relative to the wearer's body.

More recently, internal frame packs have been implemented which help to keep the load of the pack closer to the wearer's body using contoured shapes. They are designed to hold less weight and their contours may limit the range of motion of the wearer. Internal frame packs are therefore designed to balance the competing interests of weight-bearing capacity and rigidity of the pack against the comfort and mobility of the wearer, but fail to optimally address both needs at once.

Some pack frames comprise pivoting portions that attempt to follow the wearer's body through movements, such as through pivoting strap connections to a rigid frame. They fail to provide sufficiently for flexion and extension of the user's spine. For this and other reasons, these frames do not feel like a natural extension of the wearer. Furthermore, adding joints between portions of these pack frames tends to overly reduce rigidity and causes wearers to have to exert more force to keep the pack properly oriented on their backs.

SUMMARY

According to at least one embodiment, a pack frame apparatus is disclosed. The pack frame apparatus may comprise a first frame portion configured to be secured to a backpack and a second frame portion configured to be secured to the backpack. These first and second frame portions may provide structural rigidity to the backpack when secured to the backpack. The first frame portion may be configured to be secured to shoulder straps of the backpack, and the second frame portion may be configured to be secured adjacent to a waist strap of the backpack. The apparatus may also include a joint joining the first and second frame portions to allow relative pivotal movement of the first and second frame portions around a first axis and to allow resilient relative pivotal movement around a second axis.

The first axis may be oriented approximately normal to a coronal plane, and the second axis may be approximately parallel to the coronal plane.

The joint may comprise a resilient member positioned between the first and second frame portions. The joint may further comprise a rigid member, wherein the resilient member is positioned between the rigid member and at least one of the first and second frame portions. In some embodiments, the joint may further comprise a rigid member positioned between the resilient member and at least one of the first and second frame portions. In yet further embodiments, the joint may be biased to orient the first and second frame portions in a default relative orientation due to resilience of the resilient member.

The joint may be removably attached to the first and second frame portions. The joint may also be biased to orient the first and second frame portions to a default relative orientation. The joint may have uneven thickness around the first axis. At least two portions of the joint may interlock in a default relative orientation of the first and second frame portions. The joint may interlock with at least one of the first and second frame portions in a default relative orientation of the first and second frame portions, and the joint may be configured to selectively tighten and loosen the joining of the first and second frame portions.

In another exemplary embodiment, a flexible pack is provided, comprising an upper frame configured to be positioned in the pack adjacent to a torso portion of a user above the user's waist; a pair of shoulder straps configured to attach to the upper frame and wrap around the shoulders of the user; a lower frame configured to be positioned in the pack adjacent to a torso portion of a user adjacent to the user's waist; a waist strap configured to attach to the backpack adjacent to the lower frame; a storage pouch portion attached to at least one of the upper and lower plates which is adapted to removably hold equipment; and a flexible joint joining the upper and lower frames, the flexible joint allowing relative motion of the upper and lower frames in a pivot direction and allowing resilient relative motion in a torsional direction.

The flexible joint may be positioned in the backpack relative or near to a lumbar area of the user. The flexible joint may comprise an elastic portion positioned between the upper and lower frames. The flexible joint may comprise a rigid portion positioned between at least one of the upper and lower frames and the elastic portion. The flexible joint may be selectively tightenable to adjust a range of relative motion of the upper and lower frames in at least the torsional direction. The flexible joint may permit relative pivotal motion of the upper and lower frames of at least about 45 degrees in the pivot direction and may permit relative torsional motion of at least about 20 degrees in the torsional direction. The flexible joint may be biased to orient the upper and lower frames in an upright position.

In some embodiments, the upper and lower frames may be shaped to conform to a rear portion of a human body.

In another exemplary embodiment, a method of providing a pack frame apparatus is disclosed, with the method comprising providing a first plate and a second plate, the plates being adapted to provide structural support to a pack frame, the first plate being positioned for support of an upper back portion of a user through attachment to a shoulder strap, the second plate being positioned for support of a lower back portion of the user through attachment to a waist strap; and pivotally joining the first plate with the second plate, the first and second plates being relatively rotatable in a first direction and being resiliently relatively rotatable in a second direction.

Joining the first plate with the second plate may comprise inserting a resilient member between the first and second plates and joining the first and second plates around the resilient member for pivotal movement along the first direction.

The method may also comprise attaching the joined first and second plates with a backpack having shoulder straps and a bag, pouch, or other type of storage compartment. The method may also comprise adjusting the range of relative rotation of the first and second plates in at least the second direction by tightening or loosening a member joining the first and second plates.

In some embodiments, the relative rotation between the first and second plates may be biased to assume a default position in at least one of the first and second directions.

The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings and figures illustrate a number of exemplary embodiments and are part of the specification. Together with the present description, these drawings demonstrate and explain various principles of this disclosure. A further understanding of the nature and advantages of the present invention may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label.

FIG. 1A illustrates a rear perspective view of a pack frame according to an embodiment of the present disclosure.

FIG. 1B illustrates the pack frame shown in FIG. 1A relative to the remainder of an exemplary backpack.

FIG. 2A is a rear plan view of the pack frame of FIG. 1A.

FIG. 2B is a front plan view of the pack frame of FIG. 1A.

FIG. 2C is a left side plan view of the pack frame of FIG. 1A next to a profile of a wearer.

FIG. 3A is an exploded rear perspective view of a pack frame joint according to an embodiment of the present disclosure.

FIG. 3B is an exploded front perspective view of the joint of FIG. 3A.

FIG. 3C is an exploded bottom view of the joint of FIG. 3A.

FIG. 3D is an exploded side view of the joint of FIG. 3A.

FIG. 4A is a bottom section view of the joint of FIG. 2B through section lines 4A in FIG. 2B.

FIG. 4B is a side section view of the joint of FIG. 2B through section lines 4B in FIG. 2B.

FIG. 5A is an illustration of an upright user positioned relative to a pack frame apparatus according to the present disclosure.

FIG. 5B is an illustration of a turning user positioned relative to a pack frame apparatus according to the present disclosure.

FIG. 5C is an illustration of a leaning user positioned relative to a pack frame apparatus according to the present disclosure.

While the embodiments described herein are susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, the exemplary embodiments described herein are not intended to be limited to the particular forms disclosed. Rather, the instant disclosure covers all modifications, equivalents, and alternatives falling within the scope of the appended claims.

DETAILED DESCRIPTION

According to some embodiments of the present disclosure, a pack frame apparatus is provided that provides rigidity to a pack while following the natural movement of wearers and helping wearers to bear loads in a normal orientation. Thus, these embodiments may reduce fatigue, increase weight bearing capacity, and provide a more natural and comfortable feel to wearers.

A pack frame apparatus may comprise two frame portions or plates that are joined to each other by a joint that allows relative pivotal movement of the frame portions around a first axis and allows resilient relative pivotal movement around a second axis. A first frame portion may be positioned adjacent to the upper torso of wearers, and the second frame portion may be positioned adjacent to the lower torso, near or below the waist. A joint between the frame portions links them together while allowing them to rotate relative to each other in multiple directions. For example, the joint may connect the frame portions while allowing relative pivotal movement around the first axis when wearers lean laterally (i.e., left or right) while also allowing relative movement of the frame portions when wearers exert torsional forces on the plates (i.e., turning, left/right or up/down at the lower back). See, e.g., FIGS. 5A-5C.

Thus, the pack frame apparatus can accommodate multiple degrees of freedom at the back of the user. The joint may be designed with a resilient portion that allows a limited range of motion compared to a primary direction of pivotability of the joint, thereby providing a limited amount of “give” to the frame and increasing comfort, shock absorption, and adaptability of the frame to active wearers. Because the range of motion afforded by the resilient portion is limited, the flexibility of the joint does not sacrifice an undue amount of rigidity and weight bearing capacity.

In some embodiments, the joint may be adjustable, thereby providing a varying degree of restriction to the relative movement of the frame portions. By tightening or loosening the joint, the frame portions may become more rigidly or flexibly attached to each other. This may provide adaptability to the frame, where wearers may choose the amount of rigidity desired for a particular task at hand.

The joint may be designed to assist the user in orienting the frame portions in one or more particular relative position. For example, the joint may be designed with notches and grooves that coincide with each other when the frame portions are vertically aligned, and wearers must therefore overcome extra resistance to reorient the frame portions by removing the notches from the grooves as they turn in one or more direction. Other structures, such as nubs and depressions, may alternatively be used. Similarly, the joint may be configured with materials that resiliently bias relatively rotated frame portions into a preferred default position.

While reference herein is made to a frame for a backpack, it will be appreciated that the scope of the disclosure may also include frames for other devices and equipment worn on a moving body (e.g., the human body), including, for example, rucksacks, knapsacks, messenger bags, bookbags, hydration packs, fanny packs, sling bags, duffel bags, satchels, parachutes, and other cargo-carrying wearable vessels. Application of the principles and elements of the present disclosure may find beneficial use in various outdoor activities, including military, sports, travel, and other industries. Elements of the present disclosure may be applied in other body-conforming devices, such as body armor (e.g., security vests), sports equipment (e.g., protective body pads), and harnesses.

The present description provides examples, and is not limiting of the scope, applicability, or configuration set forth in the claims. Thus, it will be understood that changes may be made in the function and arrangement of elements discussed without departing from the spirit and scope of the disclosure, and various embodiments may omit, substitute, or add other procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to certain embodiments may be combined in other embodiments.

Turning now to the figures, FIG. 1 A illustrates a rear perspective view of a pack frame 100 according to an embodiment of the present disclosure. The pack frame 100 may include an upper frame portion 102 and a lower frame portion 104 joined by a joint 106. The upper frame portion 102 may correspond to a portion of a pack arranged to be adjacent to a wearer's upper torso, and the lower frame portion 104 may correspond to the wearer's lower torso. The joint 106 may be oriented to pivotably join the upper and lower frame portions 102, 104 in or around the lumbar area of a wearer. See also FIGS. 5A-5C.

As used herein, the “rear” of the pack frame 100 faces the back of the wearer when worn, and the “front” of the pack frame 100 faces away from the wearer, such as toward attached backpack compartments or other cargo space.

The upper and lower frame portions 102, 104 may comprise a generally rigid, lightweight material. In some embodiments, the frame portions 102, 104 may comprise a composite material, such as, for example, carbon fiber or fiberglass. Plastics, metals, wood, and combinations thereof may also be used for some or all of the frame portions 102, 104, such as, for example, to provide additional resilience or rigidity to sections of the frame portions 102, 104. The frame portions 102, 104 may be molded or otherwise formed with contours providing flexibility and easier attachment of backpack features to the frame portions 102, 104. In some embodiments, the contours of the frame portions 102, 104 may be shaped to direct cargo away from the surface of the wearer's body or to take the shape of certain types of cargo. For example, upper flanges 108 may be curved away from the wearer to facilitate strapping the flanges 108 to a cylindrical element such as a bedroll.

In some embodiments (not shown), the curvature of the frame portions 102, 104 may generally correspond to a backside of a human, with a lumbar portion (around joint 106) following the lumbar area of a wearer, the upper frame portion 102 having an upper end (near flanges 108 and shoulder area 114) that follows the contours of the upper back of the wearer, and the lower frame portion 104 extending from the joint 106 with a contoured area 118 following the lower back and gluteal region of the wearer's body. In this configuration, the frame portions 102, 104 may fit more closely to the wearer, bringing the center of gravity of the backpack closer to the wearer's center of gravity. In other configurations, portions of the frame portions 102, 104 may be contoured toward the wearer while other portions curve away.

The upper frame portion 102 may comprise upper flanges 108. These flanges 108 may be adapted to extend vertically higher than the wearer's shoulders or shoulder blades. The upper flanges 108 may provide rigidity to the over-shoulder region of the pack while also providing limited flexibility in that area due to the thickness and materials used in their construction.

The perimeter of the upper frame portion 102 may comprise attachment slots 110 configured to attach to a pack, e.g., pouches, straps, and/or other backpack features. In some embodiments, the attachment slots 110 may be configured on the upper frame portion 102 to allow wearers to change selectively the position of straps, bags, pouches, cords, pads, cushions, and other features. The lower frame portion 104 may also comprise attachment slots 110 (not shown) to attach a waist strap, sleep roll, pouch, or other features of a pack.

A surface of the upper frame portion 102 may comprise generally horizontal strap slots 112, such as in the shoulder area 114 of the upper frame portion 102. The strap slots 112 may provide an attachment point for shoulder straps that extend around the wearer's shoulders. See FIG. 1B. Eight strap slots 112 are shown in the figures, but more or less may be used. When using multiple strap slots 112, the shoulder straps may be repositioned to accommodate different wearer sizes or strap lengths. The strap slots 112 may also provide additional flexibility and ventilation to the shoulder area 114, thereby providing additional comfort to wearers by permitting airflow and bending near their joints. Strap slots 112 may also be used to decrease the weight of the pack frame apparatus 100. In some embodiments, the strap slots 112 are covered or obscured by bags or other enclosures, and thus may not provide airflow. In some embodiments, the strap slots 112 may be used to attach backpack elements and cushions, similar to the attachment slots 110 described above. Strap slots 112 may also be positioned on the upper pack frame 102 in a position other than the shoulder area 114 where ventilation, flexibility, or attachment points are desired. In some arrangements, the lower pack frame 104 may comprise strap slots 112. Lower pack frame 104 strap slots 112 may be used to attach the lower portion of a shoulder strap or to attach waistband straps.

The lower pack frame 104 may comprise an opening 116 and a contoured area 118. The opening 116 may reduce the weight and increase flexibility of the pack frame apparatus 100. The opening 116 may also provide a relief opening for the lower back or sacral areas of wearers by distributing weight of the pack to the sides of the spinal column and toward the iliac crests of the pelvis. The opening 116 may also be configured to receive a pad for this area of wearer.

The contoured area 118 may provide a transition between the portion of the lower pack frame 104 attached to joint 106 and the bottom end of lower pack frame 104. The contoured area 118 may facilitate easier attachment of curved bags and other cargo. In some embodiments, the contoured area 118 may also follow the natural curve of the lower back of a wearer to improve comfort and decrease the amount of flexure of the lower pack frame 104 needed to conform to the shape of the wearer's body.

FIG. 1B illustrates a pack frame 100 shown relative to the remainder of an exemplary backpack. The pack frame 100 is attached to the backpack. A main pack portion 120 may include one or more pouch or load-carrying pockets and may be secured to extend rearward from the upper pack frame 102, and a second pouch 122 and one or more side pouch 124 may be adjacent to the lower pack frame 104. Shoulder straps 126 may extend from the upper pack frame 102 (e.g., from strap slots 112) and attach to another portion of the upper pack frame 102 (e.g., at attachment slots 110), the lower pack frame 104, or to pouches or other material on the backpack. The shoulder straps 126 may be configured to wrap around the shoulders and upper body of a wearer. Waist straps 128 may extend from the lower end of the backpack, such as from an attachment to the lower pack frame 104 or a lower portion of the upper pack frame 102. The waist straps 128 may be configured to connect to each other after wrapping around the lower back, waist, or pelvic area of a wearer, such as by a buckle. Additional and alternative configurations of pouches, straps, cords, pads, and other backpack elements will be apparent to those skilled in the art of backpack design and having the benefit of the present disclosure.

FIGS. 2A-2C show alternate views of the pack frame 100 of FIGS. 1A-1B. FIG. 2A is a rear plan view, FIG. 2B is a front plan view, and FIG. 2C is a left side plan view. FIG. 2C also shows the profile of an exemplary wearer next to the pack frame 100. As shown in these figures, the upper pack frame 102 overlaps the lower pack frame 104 in and around the region where the joint 106 is located. In these embodiments, the lower pack frame 104 is positioned forward relative to the upper pack frame 102 at the joint 106, but in other embodiments, their relative positions may be reversed.

Positioning the upper pack frame 102 closer to the wearer than the lower pack frame 104 may provide more contact between the lower pack frame 104 and the cargo carried by the backpack, thereby facilitating attachment of the cargo to the lower pack frame 104. The joint 106 may also be easily adjustable, since the adjustment cap 300 may face the wearer's body.

When their relative positions are reversed, positioning the lower pack frame 104 closer to the wearer than the upper pack frame 102 may be beneficial in improving shock absorption capability of the pack frame 100. When the pack frame 100 is worn, contact between the lower pack frame 104 and the wearer may apply a constant force against the lower pack frame 104 that may not be present if the lower pack frame 104 is positioned behind the upper pack frame 102 at the joint 106. Thus, adjustments to the position or movement of the wearer may more directly and granularly be responded to by relative rotation of the upper and lower pack frames 102, 104 at the joint 106 with the lower pack frame 104 positioned closer to the wearer than the upper pack frame 102.

With the upper pack frame 102 positioned closer than the lower pack frame 104, the lower pack frame 104 may not be in constant contact with the lower torso of the wearer and may potentially not follow the wearer's movements as closely. FIG. 2C in particular shows how the curvature of the pack frame 100 relates to a curvature profile of a back of a wearer. In other embodiments, the pack frame 100 may roughly follow the curve of the spine, with the joint 106 at about the waist or upper sacral region of the body.

The rear side 200 of the upper pack frame 102 and the rear side 202 of the lower pack frame 104 may be fitted with cushions or padding to improve comfort, grip, and/or zonal flexibility of the pack frame 100 against the wearer.

FIGS. 3A-3D show exploded views of the joint 106 relative to the upper and lower pack frames 102, 104. FIG. 3A is a perspective rear view, FIG. 3B is a perspective front view, FIG. 3C is a bottom view, and FIG. 3D is a side view. Along a central axis (A), the rearward direction extends toward the end of the joint 106 having an adjustment cap 300, and the forward direction extends toward the end of the joint 106 having an internal cap 308. A first resilient member 302 is positioned between the adjustment cap 300 and the upper pack frame 102. A protective ring 304 is positioned between the first resilient member 302 and the upper pack frame 102. A second resilient member 306 is positioned between the upper pack frame 102 and the lower pack frame 104. An internal cap 308 is attachable to the adjustment cap 300 to hold the lower pack frame 104 between the internal cap 308 and the second resilient member 306.

The adjustment cap 300 may be comprised of a rigid material, such as, for example, a metal or polymer. The outer surface of the adjustment cap 300 may be configured with ridges 310. The ridges 310 may facilitate hand-tightening of the adjustment cap 300 relative to the rest of the joint 106. In some embodiments, the outer surface may have holes or other features to receive tools to tighten the cap 300. The stem 312 of the adjustment cap 300 may be threaded. The frontal face 314 (see FIG. 3B) of the adjustment cap 300 may be generally flat. The adjustment cap 300 may be threadably attachable to the internal cap 308 using the stem 312 and threads on the internal cap 308. The threaded attachment of the adjustment cap 300 and the internal cap 308 may tighten or loosen the connection between the upper and lower pack frames 102, 104, thereby adjusting the force required to move the upper and lower pack frames 102, 104 relative to each other, as described in further detail below.

The first resilient member 302 may be comprised of a relatively resilient or elastic material, such as, for example, rubber or a flexible polymer or composite. If an elastomer is used, the elastomer may be chosen to provide dampening qualities, even if the member 302 is not immediately elastic. The resilient member 302 is generally annular in shape and sized to receive the stem 312 of the adjustment cap 300 through an opening in its center. Other shapes securable between the adjustment cap 300 and the upper pack frame 102 may also be implemented, such as, for example, a partial annulus (i.e., C-shape), a square having an opening in its center, and the like. The rearward surface 316 of the first resilient member 302 may be generally flat and engage the frontal face 314 of the adjustment cap 300. The surface profiles of the rearward surface 316 and the frontal face 314 may therefore correspond to each other, and non-planar shapes may also be implemented. For example, a curved rearward surface 316 may fit with a frontal face 314 that has a correlating curved surface shape.

In some embodiments, the rearward surface 316 may comprise a circumferential lip (not shown) extending rearward from the edge of the rearward surface 316. The circumferential lip may help keep the first resilient member 302 aligned with the adjustment cap 300 and may extend around the outside edge of the frontal face 314 of the adjustment cap when the joint 106 is assembled. The circumferential lip may prevent the adjustment cap 300 from sliding relative to the rearward surface 316 when the joint 106 is torsionally flexed (e.g., around axes B or C in FIG. 5B).

The thickness (t₁) of the outer perimeter or circumference of the first resilient member 302 may vary around the central axis (A) of the joint. See, e.g., FIGS. 3C and 3D, showing profile views of the first resilient member 302. The thickness of the first resilient member 302 may thus follow the shape of the rear surface 317 surrounding the opening 318 in the upper pack frame 102. FIG. 3C shows the convex shape of the rear surface 317 around the opening 318 and the corresponding concave of the thickness of the first resilient member 302 extending from the rearward surface 316. As shown in FIG. 3D, the circular shape of the first resilient member 302 may cause the concave of the thickness of the first resilient member 302 to produce a convex curve when viewed from the side.

Varying thickness of the first resilient member 302 may affect the elastic properties of the pack frame 100. For example, with a convex rear surface 317 around opening 318 and a concave shaped first resilient member 302 (when viewed from its bottom profile), the first resilient member 302 may interlock and engage the rear surface 317 with the thinnest thicknesses 319-a of the first resilient member 302 oriented vertically relative to the wearer. In this configuration, rotation of the upper pack frame 102 relative to the first resilient member 302 may produce relative rotation of the convex and concave surfaces. For example, as the upper pack frame 102 is rotated relative to the joint 106 (and therefore also relative to the first resilient member 302), the position of the upper pack frame 102 may change orientation between the orientations shown in FIGS. 5A and 5C. The relative rotation may then cause the convex thicker portions 319-b of the first resilient member 302 to rotate into engagement with the convex area of the rear surface 317 and resiliently deform (i.e., compress) between the rear surface 317 of the upper pack frame 102 and the frontal face 314 of the adjustment cap 300. This deformation may require additional force and effort from the wearer to produce the rotation of these elements. If the upper pack frame 102 is rotated back from the orientation of FIG. 5C to the orientation of FIG. 5A, the thick portions 319-b of the first resilient member 302 may then deform again (i.e., expand), assisting the wearer in completing this motion. In such embodiments, the surface features of the upper and/or lower pack frames 102, 104 that interact with (e.g., interlock with) the resilient members 302, 306 may be referred to as portions of the joint. The first resilient member 302, ring 304, and second resilient member 306 may optionally include alignment indicators 342 to assist in properly aligning them when assembling the joint 106.

The resistance and assistance provided by the first resilient member 302 when making lateral rotation of the upper pack frame 102 relative to the joint 106 may beneficially establish a “default” or “at rest” orientation of the pack frame 100, where potential energy in the joint 106 is at its lowest. The default orientation of the pack frame 100 may be beneficially configured as an upright, weight-bearing position for the wearer. This orientation may provide the wearer with assistance in keeping the pack upright and keeping upright posture, but other orientations may be selected, as required in each individual embodiment. In some embodiments, the shape (e.g., curvature) of the first resilient member 302 may thus be configured to provide a “snap-back” position and an orientation of the pack frame 100 from which increased effort may be required to move the resilient member 302. As the upper pack frame 102 is reoriented, the first resilient member 302 may be configured to bias the upper pack frame 102 back to a default orientation relative to the joint 106 and/or lower pack frame 104.

The first resilient member 302 may also act as a shock absorber which dampens vibration or other forces between the adjustment cap 300 and the upper pack frame 102. This may enhance comfort of the pack frame, decrease wear on rigid components of the frame, and allow relative pivoting or rotational movement between elements of the pack frame along an axis perpendicular to axis A. Shock absorption and dampening may be provided around three axes of rotation. See, e.g., FIG. 5B and related description, infra, illustrating additional rotation axes B and C.

Although the embodiments shown in the figures show a first and a second resilient member 302, 306, in some embodiments, only one resilient member may be present. If the first resilient member 302 is the one present, relative rotation between the upper and lower pack frames 102, 104 may be provided since the upper pack frame 102 may compress the first resilient member 302 against the frontal face 314 of the adjustment cap 300, and the adjustment cap 300 may be rigidly attached to the internal cap 308 and/or the lower pack frame 104. This compression may provide clearance and relative rotation between sections of the upper and lower pack frames 102, 104. In embodiments where only the second resilient member 306 is present, relative rotation between the upper and lower pack frames 102, 104 may be provided by compression of the second resilient member 306 between the front surface 330 and the surface surrounding the receiver extension 336 on the lower pack frame 104.

In some arrangements, the rear surface 317 of the upper pack frame 102 may be concave and the positions of the thin edges 319-a and thick edges 319-b may be reversed accordingly to fit the concavity of the rear surface 317 similar to how their illustrated positions correspond to the convexity of the illustrated rear surface 317. In other arrangements, the rear surface 317 may be flat, and the paired convex/concave surfaces may be the rearward surface 316 of the first resilient member 302 and the frontal face 314 of the adjustment cap 300.

Other surface features may be implemented using the design features and guidelines described herein, as will be apparent to those skilled in the art having the benefit of the present disclosure. For example, a V-shaped surface may be used in place of a concave described and illustrated herein. Furthermore, the rear surface 317 may bear ridges, nubs, or notches that align with corresponding notches, depressions, or ridges on the first resilient member 302 or vice versa. These and other like designs would bias the upper and lower pack frames 102, 104 into a default orientation and/or resist reorientation out of a default orientation while still allowing elastic deformation of the first resilient member 302 under sufficient forces, providing similar benefits to the illustrated embodiments described in greater detail above.

The ring 304 is an optional feature of the joint 106 that may be positioned between the upper pack frame 102 and the first resilient member 302. The ring 304 may be comprised of a material allowing smooth sliding motion between the ring 304 and the first resilient member 302. The ring 304 may protect the first resilient member 302 and second resilient member 306 from shear forces produced by the upper pack frame 102 as it rotates relative to the first resilient member 302 by providing a rigid surface configured to be slidable against the first resilient member 302. See also FIGS. 4A-4B and their related description, infra. The ring 304 may also have a contoured shape that follows the profile (e.g., convex/concave) of the rear surface 317 of the upper pack frame 102 and a sliding surface 320 (see FIG. 3B) of the first resilient member 302. See, e.g., the curved shape of the ring 304 in FIGS. 3C and 3D. In some embodiments, the ring 304 may be referred to as a rigid member.

In the illustrated configuration, the ring 304 may be inserted into the opening 318 in the upper pack frame 102, with circumferential ridges 322 on the ring 304 insertable into circumferential notches 324 of the opening 318 and the circumferential notches 324 of the circular groove 326 of the second resilient member 306 (see FIG. 3A). Thus, the ring 304 is not rotatable relative to the upper pack frame 102 or the second resilient member 306 after insertion. The ring 304 may be comprised of a smooth, rigid material such as, for example, nylon, that allows sliding motion of the first resilient member 302 where it contacts the ring 304 at the sliding surface 320. Thus, when the upper pack frame 102 translates laterally relative to the lower pack frame 104 and/or other portions of the joint 106 (e.g., perpendicular to axis A), the ring 304 may distribute the shear force at the opening 318 across the outside surface of the ring 304 and into the first and second resilient members 302, 306. This outside surface is relatively broad in comparison to to the thickness of the upper pack frame 102. Thus, the ring 304 may allow the upper pack frame 102 to be thin and light without cutting or otherwise shearing the first and/or second resilient members 302, 306.

In some embodiments, the ring 304 may have ridges 322 configured to engage notches (not shown) in the first and second resilient members 302, 306, thereby linking rotation of the ring 304 to the resilient members instead of to the upper pack frame 102. It may be beneficial to configure the ring 304 in this manner since the ring 304 and upper pack frame 102 are typically each more rigid than the resilient members 302, 306 and it may thus be easier for them to slide against each other, but the ring 304 may also need to be thinner to be able to fit between the adjustment cap 300 and the lower pack frame 104 when they are not in the default orientation dictated by the shape of the resilient members 302, 306.

The ring 304 may also have a circumferential lip 402. See FIG. 4A. This lip 402 may prevent the ring 304 from passing through the upper pack frame 102 and may provide a surface on which the first resilient member 302 may slide.

The second resilient member 306 may be comprised of a resilient, elastic material such as rubber or a flexible polymer. The second resilient member 306 may be positioned between the upper and lower pack frames 102, 104. The second resilient member 306 may have a general shape similar to the first resilient member 302, such as, for example an annular shape or another shape having an opening therein. The thickness of the second resilient member 306 may vary around the central axis A, with thinner portions 328-a and thicker portions 328-b circumferentially spaced. While two thinner portions 328-a and two thicker portions 328-b are shown herein, other configurations may include three or more alternating thinner and thicker portions instead.

In an exemplary embodiment, shown in FIGS. 3A-3D, the front surface 330 of the upper pack frame 102 may be concave (see FIG. 3C particularly), so the thicker portions 328-b may be oriented vertically and the thinner portions 328-a may be oriented laterally when the upper pack frame 102 is in the default, upright orientation relative to the lower pack frame 104. Similar to the description above regarding the shape of the first resilient member 302 and the rear surface 317, the front surface 330 and the second resilient member 306 may be formed with interlocking or adjoining surfaces that may bias the upper pack frame to a default orientation. For example, the front surface 344 of the second resilient member may have resilient setoffs or bumps (not shown) extending from the front surface 344 toward the lower pack frame 104, and the lower pack frame 104 may comprise small depressions surrounding the receiver extension 336 that receive the setoffs when the front surface 344 is in an upright orientation. Alternatively, the setoffs and depressions may be reversed, with the setoffs extending from the lower pack frame 104. In another embodiment, the setoffs and depressions may appear on the surfaces of the upper pack frame 102 and the second resilient member 306 that come into contact. With a generally constant-thickness upper pack frame 102, the thickness t₂ of the second resilient member 306 may be analogous to the thickness t₁ of the first resilient member 302, with thicker portions of one resilient member being adjacent to thinner portions of the other.

In embodiments where the ridges 322 of the ring 304 are inserted into notches 324 in the circular groove 326 of the second resilient member 306, the second resilient member 306 may simultaneously rotate around the central axis A with the upper pack frame 102. Thus, the thicker portions 328-b and thinner portions 328-a of the second resilient member 306 may remain oriented relative to the front surface 330 and the opening 318 in the same manner as when they are in the default orientation. In other embodiments, the ring 304 may not have ridges 322 or the circular groove 326 may be wide enough to receive the ridges 322 yet allow the ring 304 to rotate within the circular groove 326. In these embodiments, the second resilient member 306 may rotate independent of the upper pack frame 102.

The second resilient member 306 may comprise a central post 332 between the circular groove 326 and the central opening through the second resilient member 306. See FIGS. 3A, 3C, and 3D. The central post 332 may be an extension of the resilient material that has greater height than the thinner and thicker portions 328-a, 328-b of the second resilient member 306. The extra height of the central post 332 may increase the surface area of the second resilient member 306 that contacts the ring 304. The extra height may also allow the central post 332 of the second resilient member 306 to contact the first resilient member 302 when the joint 106 is assembled. See also FIGS. 4A-4B.

In some embodiments, the first resilient member 302 may also have a central post 334 that may come into contact with the central post 332 of the second resilient member 306. See FIGS. 3B, 3C, and 3D. Upon assembly, the distance between the sliding surface 320 and the bottom of the circular groove 326 may therefore be about equal to the height of the ring 304. In this configuration, the ring is securely held in place by the resilient members 302, 306 and the opening 318 of the upper pack frame 102, even during rotation around axis A or another axis perpendicular thereto. A close fit may thus keep debris and dirt out of the joint 106 and keep the joint clean and operating smoothly.

The second resilient member 306 may rotate independent of the lower pack frame 104, such as by rotating around a receiver extension 336 coming from the lower pack frame 104. The receiver extension 336 may receive the internal cap 308 from the front of the joint 106 and may fit within the first and/or second resilient members 302, 306 of the joint 106 upon assembly as well. See also FIGS. 4A-4B. The surface of the receiver extension 336 may beneficially be at a 10-degrees-or-greater angle relative to the central axis A. In a preferable embodiment, this surface may be at about 15 degrees relative to the central axis A to facilitate molding construction of the lower pack frame 104. In other embodiments, such as those where the lower pack frame 104 is not molded, the surface of the receiver extension 336 may be angled at less than 10 degrees relative to the central axis A. This may allow the joint 106 to be more compact and may provide more rigidity in the joint during torsional flexion.

The rear side of the lower pack frame 104 around the receiver extension 336 may be smooth and shaped to slidably receive the second resilient member 306. In some embodiments, the second resilient member 306 may be attached to the rear side of the lower pack frame 104 around the receiver extension 336 by an adhesive, interference of parts, or another attaching means. Preferably, the ring 304 may slidably rotate within the circular groove 326 relative to the second resilient member 306 if the second resilient member 306 is attached to the lower pack frame 104.

The inclusion of two resilient members may allow greater cumulative deformation of the resilient members 302, 306 by the upper pack frame 102. This may provide smoother axial rotation of the upper pack frame 102 away from the default orientation and may also provide increased biasing forces to bring the upper pack frame 102 back into the default orientation, since the resilient members may apply a force to both side surfaces 317, 330 of the upper pack frame 102. Additionally, having resilient members on each side of the upper pack frame 102 may allow easier movement of the upper pack frame 102 relative to the lower pack frame 104 around an axis perpendicular to central axis A. This torsional motion of the pack frames 102, 104 may be accommodated by compression of both of the resilient members 302, 306 on each side of the opening 318 (i.e., on opposing sides of the resilient members 302, 306). See also FIG. 5B and its related description below.

The internal cap 308 may be received by the lower pack frame 104 from the front of the receiver extension 336. The internal cap 308 may be internally threaded to receive threads of the stem 312 of the adjustment cap 300. Using a threaded internal cap 308 and stem 312, the tightness joint 106 may be adjustable to allow more or less resistance to axial and/or off-axial relative rotation of the upper and lower pack frames 102, 104. For example, tightening the threaded connection of the internal cap 308 and adjustment cap 300 may force the first resilient member 302 to partially deform (e.g., compress) into the upper pack frame 102, thereby decreasing the amount of potential deformation of the resilient member upon reorientation of the upper pack frame 102 and increasing frictional forces between the resilient member and the upper pack frame 102.

The internal cap 308 may have an outer surface 338 configured to engage an inner surface 340 of the receiver extension 336. For example, the outer surface 338 may be faceted such that it may be received by the inner surface 340 without allowing rotation of the internal cap 308 after insertion. In another embodiment, the outer surface 338 may have one or more extension that may be received by the inner surface 340 that prevents rotation of the internal cap 308, or vice versa. The internal cap 308 may thus be restricted from rotating relative to the lower pack frame 104 due to the engagement of the outer and inner surfaces 338, 340. By preventing rotation of the internal cap 308, the adjustment cap 300 may be more easily turned relative to the internal cap 308 using the ridges 310. This may advantageously allow a user to adjust the tension in the joint 106 with access to only the rear end of the joint 106, as may be the case if the pack frame 100 is installed in a backpack with pouches, sleeves, and other material covering the front end of the joint 106 around the internal cap 308. The threaded connection between the adjustment cap 300 and the internal cap 308 may also be configured to prevent the internal cap 308 from being removed from the stem 312 while installed in a backpack, such as by limiting the rotation of the threads of the stem 312 at a point to prevent inadvertent removal of the internal cap 308. In this fashion, the internal cap 308 may not be easily lost or disconnected within the backpack while the pack frame 100 is installed. In some embodiments, the internal cap 308 may rotate within the receiver extension 336. In yet other embodiments, the stem 312 may lock into position upon being completely received by the internal cap 308, thereby preventing removal of the adjustment cap 300 from the internal cap 308, or the internal cap 308 may be bonded into place, such as, for example, by an adhesive between the internal cap 308 and the lower pack frame 104. In other embodiments, the adjustment cap 300 may be removably attached to the internal cap 308, so the rest of the joint 106 (e.g., resilient members 302, 306) may also be removable from the pack frame 100.

The internal cap 308 may also be attached to the stem 312 using other means, such as, for example, glue or another adhesive, a weld, press fit, or interference of parts. In some embodiments, the role of the internal cap 308 and the adjustment cap 300 may be reversed, such that the internal cap 308 may have ridges (e.g., similar to ridges 310) and a stem extending into threaded connection with a threaded hole in the adjustment cap 300. The role of other parts may also be exchanged without departing from the principles and elements of the present disclosure.

FIG. 4A shows a bottom section view through section lines 4A in FIG. 2B. FIG. 4B shows a left side section view through section lines 4B in FIG. 2B. Thus, FIGS. 4A and 4B illustrate orthogonal, central section views of the assembled joint 106. The most rearward element is the adjustment cap 300, followed by the first resilient member 302, ring 304 and upper pack frame 102, second resilient member 306, lower pack frame 104, and internal cap 308. As shown in these figures, the stem 312 of the adjustment cap 300 may extend through the internal cap 308 completely upon tightening.

The first resilient member 302 may be compressed between the frontal face 314 of the adjustment cap 300 and the receiver extension 336 into the shape shown. In this configuration, the opening in the receiver extension 336 may contact a portion of the stem 312 and therefore apply less shear force to one of the resilient members 302, 306 upon lateral movement of the lower pack frame 104 relative to the resilient members 302, 306. The adjustment cap 300 may have a stem shaft surface 400 configured to allow slidable rotation of the receiver extension 336 around the stem 312. In other embodiments, the lower pack frame 104 may be linked in rotation with the adjustment cap 300 due to the threads of the internal cap 308 in order to prevent the adjustment cap 300 from unthreading from the internal cap 308.

FIGS. 4A-4B also show the varying thicknesses of the first first and second resilient members 302, 306 and the ring 304. The thickness of the ring 304 in FIG. 4A appears thinner than the thickness in FIG. 4B due to the ridges 322 of the ring 304 being within section lines 4B. The rearward portion of the ring 304 may have a lip 402 that prevents the ring 304 from passing completely through the opening 318 in the upper pack frame 102. The lip 402 is not visible in FIG. 4B due to the increased thickness of the ring 304 subsuming the lip 402 at the ridges 322.

FIGS. 4A-4B also illustrate how the entire height of the ring 304 may contact the first and second resilient members 302, 306. The height of the ring 304 is shown to be significantly broader than the thickness of the upper pack frame 102 and is distributed across the boundary between the first and second resilient members 302, 306, so that the ring 304 may prevent shearing of the resilient members 302, 306 by the upper pack frame 102 and may also prevent the upper pack frame 102 from sliding between the resilient members 302, 306 where they come into contact with each other. For example, the ring 304 may prevent the upper pack frame 102 from coming into contact with the central posts 332, 334. The first resilient member 302 may therefore slide more easily relative to the upper pack frame 102, and it may be subject to less wear than if its central post 334 was in contact with the opening 318 of the upper pack frame 102.

The thickness of the first resilient member 302 in FIG. 4A corresponds with the thicker portions 319-b, and the thickness of the first resilient member in FIG. 4B corresponds with the thinnest thicknesses 319-a. These figures therefore show the approximate amount of compression required for the thicker portions 319-b to rotate into the position of the thinnest thicknesses 319-a. The thinner portions 328-a and thicker portions 328-b of the second resilient member 306 are also shown in FIGS. 4A and 4B, respectively, thus showing how the second resilient member 306 conforms to the front surface 330 of the upper pack frame 102. Additionally, the thicknesses 328-a, 328-b of the second resilient member 306 are greater than the thicknesses 319-a, 319-b of the first resilient member 302. If the second resilient member 306 is made of the same material as the first resilient member 302, the second resilient member 306 may therefore have a greater capacity for compressive deflection than the first resilient member 302. This may allow easier relative torsional motion of the upper and lower pack frames 102, 104 than relative lateral pivotal motion (i.e., around central axis A of the joint 106). In embodiments where the second resilient member 306 may rotate relative to the upper pack frame 102, these views also show the amount of compression needed to complete a rotation (i.e., a rotation of the thicker portion 319-b from FIG. 4B to the position of the thinnest thicknesses 319-a of FIG. 4A).

The width W of the joint 106 may be wide to improve the stability of the joint 106. A narrower width W may increase the pivotability of the joint 106 along an axis perpendicular to the central axis A, and a wider joint 106 may decrease pivotability. The opening 404 of the adjustment cap 300 is shown open, which may decrease weight and cost of materials, but in some embodiments the interior of the adjustment cap 300 may be narrower, walled off, or filled, which may increase strength and help prevent debris from getting to the front side of the joint 106. In embodiments having an through-hole at the opening 404, a user may reach to the front of the joint 106, such as to recover an internal cap 308 that comes off of the stem 312, to clean the front of the joint 106, or to hold the internal cap 308 in place while the adjustment cap 300 is tightened (in appropriate embodiments). Thus, the opening 404 in the adjustment cap 300 may be large enough to receive a finger, hand, or tool of a user depending on the purposes for which the opening 404 is designed.

The outer surfaces 406, 408 of the resilient members 302, 306, may be sloped or beveled. Sloped outer surfaces 406, 408 may resist deformation less than straight (i.e., completely horizontal or vertical) outer surfaces 406, 408, so the profile of the outer surfaces 406, 408 may increase flexibility of the joint 106 in both axial and off-axial rotation. Shaped (e.g., sloped) outer surfaces 406, 408 may also have controlled deformation, such as reduced buckling or expansion in a desired direction. Other profile shapes of the outer surfaces 406, 408 may be selected based on desired flexibility and compression characteristics of the joint 106, such as, for example, chamfered, stepped, semicircular, and other shapes that would be apparent to those skilled in the art having the benefit of the present disclosure.

FIGS. 5A-5C illustrate how a pack frame apparatus 500 may be positioned and moved relative to a user U. For convenience in viewing and understanding the operation of the pack frame apparatus 500, straps, bags, pads, and other features of a backpack that would attach to the user U or the pack frame apparatus 500 are omitted.

In FIG. 5A, the user U has the pack frame apparatus 500 positioned on his back with the upper pack frame 502 positioned relative to his upper torso and the lower pack frame 504 positioned relative to his lower back/sacral area. The upper pack frame 502 is connected to the lower pack frame 504 by joint 506. The user U is standing vertically upright (i.e., in a coronal or frontal plane vertically splitting his anterior and posterior sides), and the upper and lower pack frames 502, 504 are roughly vertically aligned at the joint 506 (i.e., also in the coronal or frontal plane). In a preferable embodiment, this upright position may be the default orientation of the pack frame apparatus 500. In this position, the weight borne by the pack frame apparatus 500 may be evenly distributed to both shoulders and both sides of the waist and hips, so the user U may feel less fatigue while bearing a load in this position. Additionally, in this position the joint 506 may optimally absorb shock along all three axes of rotation (i.e., axes A (see FIG. 3A), B, and C) since the resilient portion(s) of the joint 506 are not pre-loaded. Therefore, resilient members between the upper and lower pack frames 502, 504 (e.g., first and/or second resilient members 302, 306 of FIGS. 3A-4B) and the surfaces of the upper and lower pack frames 502, 504 near the joint 506 may be shaped to be inclined to stay in this position. In some embodiments, there may be no default orientation, and the pack frame apparatus 500 may pivot at the joint laterally (e.g., in the manner shown in FIG. 5C) without requiring additional resistance to reposition the upper and lower pack frames 502, 504 relative to each other.

FIG. 5B is an illustration of the pack frame apparatus 500 flexing in torsion due to rotation of the upper torso of the user U. The upper and lower pack frames 502, 504 are still positioned in approximately the same positions relative to the respective parts of the user U as in FIG. 5A, but now the joint 506 has flexed so that the upper pack frame 502 has rotated around axes B and/or C. Axes B and C are parallel to (or co-planar with) the coronal plane described in connection with FIG. 5A. The forward part of the joint 506 (e.g., its internal cap 308) is unmoved relative to FIG. 5A since the lower pack frame 504 has not moved relative to FIG. 5A, but the upper pack frame 502 has rotated. During energetic activities, movement of the upper pack frame 502 around axes B and C allows the pack frame apparatus 500 to be secured more closely to the user U by following his natural body motions. The amount of flexure that permits rotation around axes B and C may be limited by the compressibility and thickness of the materials used as resilient members between the upper and lower pack frames 502, 504. In an exemplary embodiment, the pack frame apparatus 500 may allow torsional rotation of up to at least about 20 degrees around axes B and/or C. Controlling the flexibility of the joint 506 may help prevent the pack frame apparatus 500 from damaging a cover, pouches, and other equipment attached thereto. Limiting the flexibility of the joint 506 using resilient materials may also allow the joint 506 to bias the upper and lower pack frames 502, 504 into the aligned position of FIG. 5A when they are in the positions of FIG. 5B or 5C.

Resilient rotation around axis B would correspond with a twisting motion of the wearer (i.e., rotation around the spine), and resilient rotation around axis C would correspond with a bending motion of the wearer (i.e., bending forward toward the toes or arching the spine). The joint 506 may facilitate one or more of these resilient rotational movements. In some embodiments, the joint 506 may also provide resilient rotational movement around axis A, as depicted in FIG. 5C.

FIG. 5C illustrates the pack frame apparatus 500 pivoting laterally at the joint 506 in response to the user U leaning laterally to his right (i.e., within the coronal plane of the joint or around an axis normal to the coronal plane). In an exemplary embodiment, the pack frame apparatus 500 may allow pivotal motion in this plane of at least about 45 degrees relative to the vertical position. In some embodiments, the pivotal motion may be at least about 30 degrees in this plane. Similar to the pack frame apparatus of FIG. 5B, the lower pack frame 504 remains motionless relative to the user U but the upper pack frame 502 rotates with his upper torso. In the embodiment shown, the joint 506 may have very low friction and resistance. In embodiments where there is curvature to a resilient member between the upper and lower pack frames 502, 504 or between at least one of the upper and lower pack frames 502, 504 and the joint 506 (e.g., an adjustment cap 300 or internal cap 308), and therefore there is resistance to relative pivoting between the upper and lower pack frames 502, 504, the lower pack frame 504 would likely rotate slightly at the joint 506 due to biasing forces provided by the resilient member(s) attempting to align the upper and lower pack frames 502, 504. The lower pack frame 504 may also be in the position shown in FIG. 5C due to straps attaching the lower pack frame 504 around portions of the user U that have not moved between FIGS. 5A and SC, such as around the pelvis of the user U.

While using the pack frame apparatus 500, the user U may naturally move in multiple directions simultaneously. For example, the user U may pivot the joint 506 while torquing the upper and lower pack frames 502, 504 simultaneously. Thus, the motions of FIGS. 5B and 5C may be enacted at once. The pack frame apparatus 500 may follow these natural movements while bearing a load and while being attached or strapped to the user U. The upper and lower pack frames 502, 504 may therefore be beneficially constructed of rigid, weight-bearing materials since the joint 506 provides flexibility at the crucial mid-torso area. The pack frame apparatus 500 may also be beneficially positioned nearer to the torso of the user U throughout these motions than a rigid pack frame would be, providing the user U with improved balance and less shaking or other motion of the pack and/or its contents while in motion.

Another embodiment may include a method of providing a pack frame apparatus. The method may comprise providing a first plate and a second plate, wherein the first and second plates may be adapted to provide structural support to a pack frame. The first plate may be positioned for support of an upper back portion of a user through attachment to a shoulder strap, and the second plate may be positioned for support of a lower back portion of the user through attachment to a waist strap. The method may also comprise pivotally joining the first plate with the second plate such that the plates are relatively rotatable in at least a first direction and resiliently relatively rotatable in a second direction. Thus, the plates may rotate in a first direction without resilient resistance, and the plates may rotate in a second direction with resilient resistance. In another embodiment, the plates may rotate in the first direction with resilient resistance as well. The resilient resistance may cause the plates to bias to a default orientation. For example, the resilient resistance may bias the plates toward a vertical, upright position with the first and second plates about parallel where they are joined together.

The first and second plates may be broad, generally flat parts and at least semi-rigid in comparison to the resilient features that join them. In some embodiments, portions of the plates may be more flexible than others, such as, for example, by having a more flexible material where they are joined, or by having openings or relief holes in portions of the plates that allow them to resiliently deflect or deform. The plates may have openings, slots, or holes through their surfaces to reduce weight, increase zonal flexibility, or for other reasons, such as those set forth above in connection with the slots 110, 112 and openings 116 of the upper and lower pack frames 102, 104.

The method may also include a step of joining the first plate with the second plate by inserting a resilient member between the first and second plates. The first and second plates may then be joined for pivotal movement along the first direction around the inserted resilient member. In another embodiment, the method may include attaching the joined first and second plates with a backpack having shoulder straps and a storage compartment. In some embodiments, the relative rotation of the first and second plates may be adjusted in at least the second direction by tightening or loosening a member joining the first and second plates. In some embodiments, this may entail adjusting part of the joint (e.g., an adjustment cap 300) relative to the rest of the joint or the plates. The relative rotation between the first and second plates may be biased to assume a default position in at least one of the at least two directions. This may be accomplished in the manner described in connection with FIGS. 3A-3D above. Additional steps may include forming and arranging the parts of the joint 106 and upper and lower pack frames 102, 104 as described above. In some embodiments, the steps of these methods may be reordered or combined.

The previous description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Throughout this disclosure the term “example” or “exemplary” indicates an example or instance and does not imply or require any preference for the noted example. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. 

What is claimed is:
 1. A pack frame apparatus, comprising: a first frame portion configured to be secured to a backpack, the first frame portion providing structural rigidity to the backpack when secured to the backpack, the first frame portion being configured to be secured to shoulder straps of the backpack; a second frame portion configured to be secured to the backpack, the second frame portion providing structural rigidity to the backpack when secured to the backpack, the second frame portion being configured to be secured adjacent to a waist strap of the backpack; a joint joining the first and second frame portions to allow relative pivotal movement of the first and second frame portions around a first axis and to allow resilient relative pivotal movement around a second axis.
 2. The pack frame apparatus of claim 1, wherein the first axis is oriented about normal to a coronal plane.
 3. The pack frame apparatus of claim 2, wherein the second axis is about parallel to the coronal plane.
 4. The pack frame apparatus of claim 1, wherein the joint comprises a resilient member positioned between the first and second frame portions.
 5. The pack frame apparatus of claim 4, wherein the joint further comprises a rigid member, wherein the resilient member is positioned between the rigid member and at least one of the first and second frame portions.
 6. The pack frame apparatus of claim 4, wherein the joint further comprises a rigid member positioned between the resilient member and at least one of the first and second frame portions.
 7. The pack frame apparatus of claim 4, wherein the joint is biased to orient the first and second frame portions in a default relative orientation due to resilience of the resilient member.
 8. The pack frame apparatus of claim 4, wherein the resilient member is configured as a shock absorber between the first and second frame portions.
 9. The pack frame apparatus of claim 1, wherein the joint is removably attached to the first and second frame portions.
 10. The pack frame apparatus of claim 1, wherein the joint is biased to orient the first and second frame portions in a default relative orientation.
 11. The pack frame apparatus of claim 10, wherein the joint has uneven thickness around the first axis.
 12. The pack frame apparatus of claim 10, wherein the joint has even thickness around the first axis.
 13. The pack frame apparatus of claim 1, wherein at least two portions of the joint interlock in a default relative orientation of the first and second frame portions.
 14. The pack frame apparatus of claim 1, wherein the joint interlocks with at least one of the first and second frame portions in a default relative orientation of the first and second frame portions.
 15. The pack frame apparatus of claim 1, wherein the joint is configured to selectively tighten and loosen the joining of the first and second frame portions.
 16. The pack frame apparatus of claim 1, wherein the joint is further configured to allow resilient relative pivotal movement of the first and second frame portions around a third axis.
 17. A flexible pack, comprising: an upper frame configured to be positioned in the pack adjacent to a torso portion of a user above the user's waist; a pair of shoulder straps configured to attach to the upper frame and wrap around the shoulders of the user; a lower frame configured to be positioned in the pack adjacent to a torso portion of a user adjacent to the user's waist; a waist strap configured to attach to the backpack adjacent to the lower frame; a storage pouch portion attached to at least one of the upper and lower plates, the storage pouch portion adapted to removably hold equipment; a flexible joint joining the upper and lower frames, the flexible joint allowing relative motion of the upper and lower frames in a pivot direction and allowing resilient relative motion in a torsional direction.
 18. The flexible backpack of claim 17, wherein the flexible joint is positioned in the backpack relative to a lumbar area of the user.
 19. The flexible backpack of claim 17, wherein the flexible joint comprises an elastic portion positioned between the upper and lower frames.
 20. The flexible backpack of claim 19, wherein the flexible joint comprises a rigid portion positioned between at least one of the upper and lower frames and the elastic portion.
 21. The flexible backpack of claim 19, wherein the flexible joint is selectively tightenable to adjust a range of relative motion of the upper and lower frames in at least the torsional direction.
 22. The flexible backpack of claim 17, wherein the flexible joint permits relative pivotal motion of the upper and lower frames of at least about 45 degrees in the pivot direction and permits relative torsional motion of at least about 20 degrees in the torsional direction.
 23. The flexible backpack of claim 17, wherein the flexible joint is biased to orient the upper and lower frames in an upright position.
 24. The flexible backpack of claim 17, wherein the upper and lower frames are shaped to conform to a rear portion of a human body.
 25. A method of providing a pack frame apparatus, the method comprising: providing a first plate and a second plate, the first and second plates adapted to provide structural support to a pack frame, the first plate being positioned for support of an upper back portion of a user through attachment to a shoulder strap, the second plate being positioned for support of a lower back portion of the user through attachment to a waist strap; pivotally joining the first plate with the second plate, the first and second plates being relatively rotatable in a first direction, the first and second plates being resiliently relatively rotatable in a second direction.
 26. The method of claim 25, wherein joining the first plate with the second plate comprises: inserting a resilient member between the first and second plates; joining the first and second plates around the resilient member for pivotal movement along the first direction.
 27. The method of claim 25, further comprising: attaching the joined first and second plates with a backpack having shoulder straps and a storage compartment.
 28. The method of claim 25, further comprising: adjusting the range of relative rotation of the first and second plates in at least the second direction by tightening or loosening a member joining the first and second plates.
 29. The method of claim 25, wherein the relative rotation between the first and second plates is biased to assume a default position in at least one of the first and second directions. 